The technical field of this invention is automatic security systems particularly automatic security systems employing computer image processing for tracking objects in a video sequence.
The goal is to track multiple people and objects (e.g., vehicles) in video sequences when the objects may be partially occluded by each other. Prior art is background differencing, which cannot handle multiple objects with merges or occlusions; template matching, which cannot handle strong object deformations; and histogram matching, which requires tracked objects to have color or grey-scale features which differentiate the people being tracked.
The new method employs the novel concept of a probabilistic templates, or p-templates, which probabilistically encode the rough position and extent of the tracked object""s image. The p-templates track objects in the scene, one p-template per object. They can be used to incorporate three-dimensional knowledge about the scene, and to reason about occlusion between the objects tracked by the p-templates. P-template tracking is robust to deformations such as arm gestures, and to strong occlusions.
This invention enables digital video camera applications that require tracking with robustness to occlusion. Our method will help to create new markets for networked digital cameras that analyze the video stream. The method is suitable for implementation on digital signal processors. Applications are in physical security, home automation, and sporting event analysis.
This invention requires video capture and digitization hardware, image processing hardware such as a digital signal processor, and a method for estimating the image size of a person standing at a given location in the image. This estimate of image size could be as described in co-pending U.S. Patent Provisional Application No. 60/083,711 entitled xe2x80x9cMETHOD AND APPARATUS FOR MAPPING A LOCATION FROM A VIDEO IMAGE TO A MAP,xe2x80x9d now U.S. patent Ser. No. 09/292,499.